In a variety of medical procedures a fluid is injected into a patient for the purpose of diagnosis or treatment. For example, a contrast media fluid is injected into a patient to improve computed tomography (CT), angiographic, ultrasound, or magnetic resonance imaging (MRI) procedures. During such procedures, there are typically time periods where a contrast injector is connected to a patient, but procedural preparations delay the injection of the contrast media fluid. Since no fluid is flowing through the injection site during the delay, if the delay is long enough, blood at the injection site may begin to coagulate or clot. If a significant blood clot forms within the fluid path, the injection of contrast media fluid may be hindered.
One approach to keep the vein open before the main injection begins, is to slowly drip the contrast media. However, this wastes contrast media, which, as used in MRI procedures, is very expensive. To prevent this premature and undesirable restriction or closure of the fluid path, without waste of contrast media, some injector systems include a second syringe, which is typically filed with a saline solution. During the time period when no contrast fluid is being injected, these injectors will intermittently dispense small bursts of saline into the fluid path.
There are, however, a number of problems associated with the use of a second syringe filled with saline. First, the addition of a second syringe can significantly increase the cost and complexity of the injector. Second, technologists are forced to set up two syringes with two different fluids, connecting Y-tubing instead of a single line tube, and must go through a more involved air purging process to rid both syringes and the Y-tubing of air. Y-tubing also is typically more expensive than a single line tube, thus also increasing the cost to the consumer. Finally, an imaging suite has to order and stock extra syringes for saline use and must dispose of additional medical waste after the saline syringes are used.
Accordingly, there is a need to simply and cost effectively keep a vein open during procedures without the use of a second syringe and a saline drip solution.